Essential hypertension or sustained high blood pressure is a genetic disorder that affects 20% of the Caucasian population and predisposes individuals to other disorders such as stroke, and renal and cardiovascular disease. Hypertension is also known to cluster with obesity and other disorders such as non-insulin dependent diabetes (NIDDM), atherosclerosis, vascular disease and dyslipidaemia in a metabolic syndrome known as Syndrome X. Identifying the cause of hypertension and Syndrome X susceptibility has been hindered by the complex genetics of the disorder and its interaction with environmental triggers. Candidate gene approaches offer a method to identify genes involved and have been used successfully to identify two genes involved in the disorder (Jeunemaitre X, Soubrier F, Kotelevtsev Y V, Lifton R P, Williams C S, Charru A, Hunt S C, Hopkins P N, Williams R R, Lalouel J, Corvol P. Molecular Basis of Human Hypertension: Role of Angiotensinogen. Cell 1992; 71: 169-180, and Ying L, Zee R Y L, Griffiths L R, Morris B J. Association of a RFLP for the insulin receptor gene, but not insulin, with essential hypertension. Biochem Biophys Res Comm 1991; 181: 486-492).
Results from these studies may lead to better targeted treatments. If the genes that cause susceptibility to Syndrome X disorders can. be identified, then treatments for specific gene defects can be targeted. At present such targeted treatment strategies are not available, but once diagnostic tests for disease susceptibility in these fields are developed such treatments will become available. At present, the only available treatments for these disorders are pharmaceutical based medications that are not targeted to an individual's actual defect; examples include ACE inhibitors and diuretics for hypertension, insulin supplementation for NIDDM, cholesterol reduction strategies for dyslipidaemia, anti-coagulants, .beta. blockers for cardiovascular disorders and weight reduction strategies for obesity.
However, no gene approaches have to date provided for diagnosis of predisposition or susceptibility to hypertension or other components of Syndrome X to enable treatment before the symptoms and effects of disease become established.